Passage: In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank. Pollution is the introduction of substances that cause adverse changes in the environment. _____(1)_____ are mainly four types of pollution, namely air pollution, water pollution, soil pollution and noise pollution. Air pollution refers to the release of _____(2)_____ contaminants such as chemicals, toxic gases and particulate _____(3)_____ the earth's atmosphere. Water pollution is said to occur when toxic pollutants and particulate matter are introduced into water bodies _____(4)_____ lakes, rivers and seas. Soil pollution refers to the degradation of land due to the _____(5)_____ of chemicals or man made substances in the soil. Question: Select the most appropriate option to fill in blank number 4.

1. like as
2. likely
3. such as
4. e.g.